JP2001090765A - Gas spring delaying in return stroke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas spring for controlling a return speed of a piston rod by using only compressed gas. SOLUTION: A gas spring has a first gas chamber communicated with a second gas chamber via a calibration orifice, and controls a speed for gas to return up to the second chamber from the first chamber to thereby control a speed for a piston rod of a cylinder to return up to the extension position. The speed for the piston rod to return up to the extension position can be sufficiently delayed until a stamped part is not damaged by raising the part from a lower side die by the gas spring. A composite shell of the gas spring is formed of a material having high heat conductivity so as not to overheat the gas spring and so as to increase the cycle number to be completed in a prescribed period, and includes the material. The gas spring is a complete self- contained shape, resists a movement up to a contraction position of the piston rod by using only gas, offers force for moving the piston rod up to the extension position, and controls the speed for the piston rod to return to the extension position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates generally to gas springs, and more particularly, to gas springs that delay return travel.

[0002]

BACKGROUND OF THE INVENTION A typical gas spring suitable for stamping applications is assembled using a working rod connected to a piston. The piston is slidably housed in a cylinder having a cavity, and the cavity is pre-filled to a predetermined pressure with an inert gas such as nitrogen. When the rod and piston are pushed into the cavity, the gas inside is compressed, and when the force applied to the rod ceases, the compressed gas in the cavity immediately pushes the piston and rod toward their fully extended position. .

[0003] In some die-cutting applications, a stamped part can be removed from the cavity of the lower die using a gas spring adjacent the lower die.

[0004]

When a general gas spring is used, a problem occurs in the return stroke of the upper die. Because the gas spring returns immediately and quickly to its fully extended position, the stamped part is quickly removed from the lower die and lifted. For components having at least some surface area, the stamped component may be distorted by the gas spring returning rapidly toward its extended position,
Or bending, which adversely affects the quality of the stamped part.

[0005] To delay or control the return of the piston and rod to the extended position, some conventional gas springs have utilized mechanical or electronic control over the gas spring. Such control is undesirable and adds to the cost and complexity of the gas spring. Another type of gas spring, such as that disclosed in U.S. Pat.No. 5,823,513, uses hydraulic oil in one chamber, compressed gas in the other chamber, and a momentary valve below the stroke of the gas spring using a lag valve. Causing a pause. This pause is provided to prevent damage to the press for a number of reasons. An important aspect of the delay cylinder is its ability to withstand and / or dissipate the heat generated during use.

[0006]

SUMMARY OF THE INVENTION A gas spring is connected to a first gas chamber in communication with a second gas chamber via a calibration orifice.
Gas from the first chamber to the second chamber
Of the cylinder, thereby controlling the rate at which the piston rod of the cylinder returns to its extended position. Desirably, the rate at which the piston rod returns to its extended position can be sufficiently slow so that the gas spring does not damage the stamped part by lifting the part from the lower die. The gas spring cylinder assembly includes highly thermally conductive components to prevent the gas spring from overheating and to increase the number of cycles to be completed in a given time period. Desirably, the gas spring is fully self-contained, utilizing only gas to resist movement of the piston rod to a retracted position, providing a force to move the piston rod to its extended position, and Controls the speed at which it returns to its extended position.

[0007] Objects, features, and advantages of the present invention include providing a gas spring as follows. The gas spring has a controlled rate of returning to its extended position, does not use hydraulic oil or other liquids, is self-contained, uses only compressed gas, and generates heat from the gas spring. The use of highly thermally conductive components to increase the dissipation of heat and remove heat from the gas spring by conduction, can have a relatively short cycle time, can use a surge tank, and can use active electronic control or It requires no manual control and has a relatively simple design and economical productivity and assemblability, and a long service life in use.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects, features and advantages of the present invention will become apparent from the following detailed description of the preferred embodiment and the best mode, the appended claims, and the drawings. .

Referring to the drawings in more detail, FIG. 1 shows a plurality of gas springs 10, 13 of a stamping press 11. The press 11 has an upper die 12 that is held by an upper platen 14 of the press 11 and is movable toward a lower die 16 that is fixed to a lower platen 18 of the press 11, and has an upper die 12 and a lower die 12. The sheet metal blank 20 arranged between the dies 16 is stamped and formed. Gas spring 13 with upper die
The gas spring 10 may be attached to the lower die 16 by attaching the gas spring 10 to the lower die 12, or the gas springs 10 and 13 may be held by the platens 14 and 18 of the press 11. Desirably, each gas spring 10, 13 has a piston rod extending therefrom.
With 24. Preferably, the piston rod 24 is
Attached to upper and lower draw rings 26, 27 for engaging, positioning and holding blanks 20 to be stamped against 12,16. Lower gas spring 10
A draw ring 27 also lifts the formed part from the lower die to facilitate movement of the part and replaces it with the next blank 20 to be formed.

As shown in FIGS. 2 and 3, the gas spring
10 preferably has an outer generally cylindrical shell 30 surrounding a cylinder body 32 in which a piston rod assembly 34 reciprocates. The shell 30 is preferably formed of a highly thermally conductive material such as copper or aluminum to enhance the transfer of heat removed from the gas spring 10. Gas spring 10
Annular fins 36 may be formed around the upper end of shell 30 to further enhance the transfer of heat removed from the shell.
To further improve the heat transfer from the gas spring 10,
The shell 30 includes a plurality of blind bores 38 extending into adjacent blind bores 39 of a mounting plate (base plate) 72.
And each of the bores 38, 39 may be provided with a heat pipe. The heat pipe 40 is an elongated tubular rod formed of a material having high thermal conductivity, closed at both ends, and contains a large amount of working fluid and a central shin at a controlled pressure. When the fluid reaches a certain temperature at one end of the heat pipe 40, the fluid evaporates and rises in the heat pipe. The heat pipe 40 is such that a sufficient temperature difference exists between its ends to allow the evaporated working fluid to recondense at the other end, thereby dissipating heat at this phase transition. Designed and deployed. The liquefied working fluid returns through the shin and begins another cycle. Suitable heat pipes 40 are commercially available from Thermacore, Inc. of Lancaster, PA.

The cylinder body 32 has a generally cylindrical side wall 42, preferably welded to a base 44. The side walls 42 and the base 44 are preferably formed of a thermally conductive material such as steel and are capable of withstanding the pressure exerted on the cylinder body 32 by the compressed gas in the gas spring 10 and the force exerted by the retaining wheel 48. It is strong enough. An annular groove 46 formed inside the side wall 42 is configured to receive a retaining ring 48 that retains the piston rod assembly 34 inside the cylinder body 32. The generally helical groove formed around the outer surface 50 of the side wall 42 defines the cylinder body 32 and the shell 30.
Define a fluid passage 52 therebetween. Annular annular grooves 54, 56 formed outside the opposite ends of the fluid passages 52 receive the O-rings 58, 60 and provide fluid tightness between the shell 30 and the cylinder body 32. Provide a (fluid tight) seal. Restricted passage with calibrated flow area
62 communicates the fluid passage 52 with a first gas chamber 64 of the cylinder body 32. A bore 66 passing through the base 44 of the cylinder body 32 communicates the second gas chamber 68 with a passage 70 formed in a mounting plate 72 to which the shell 30 and the cylinder body 32 are connected.

The mounting plate 72 is connected to the base 44 of the cylinder body 32 by one or more cap screws 74, preferably received in a threaded blind bore in the base,
The cap screw 75 connects to the shell. The mounting plate 72 is preferably configured to be fixed directly to the die 12, 16 or one of the platens 14, 18 of the press 11 by a cap screw 76 (FIG. 2). A gas filler valve 78 is provided at the inlet 80 of the mounting plate passage 70 to allow compressed gas to be supplied into the gas spring 10. In use, this valve is always closed by plug 82. The branch passage 84 extends through the mounting plate 72 into the shell 30 to communicate the fluid passage 52 with the passage 70 of the mounting plate 72. Accordingly, the passage 70 in the mounting plate 72 allows the second gas chamber 68 in the cylinder body 32 to communicate with the cylinder body 32.
And a fluid passage 52 defined between the shell 30.
An O-ring is provided between base 44 and plate 72 to provide a fluid tight seal therebetween. Another O-ring surrounds passageway 84 between shell 30 and mounting plate 72 and provides a fluid tight seal therebetween.

Annular bearing and seal assembly 86
Is received inside the cylinder body 32 and the housing 88
Having. The housing engages a retaining ring 48 that holds an assembly 86 within the cylinder body 32 with a small diameter upstream end 90 that provides a generally radially outwardly extending shoulder 92. The housing 88 has a groove 94 formed around its outer surface, and the housing 88 and the cylinder body
The seal 32 is configured to receive a seal ring, such as an O-ring 96, to provide a fluid tight seal therewith. Backing (ba
Preferably, a ck-up 97 is provided to ensure the integrity of the seal under high pressure. Such a backing may be required for all fixed seals of the gas spring 10. The through bore 98 slidably receives the piston rod for reciprocation and defines an annular surface 100 sized to closely receive the piston rod 24 therethrough.
When the rod reciprocates, the rod seal 104 abutting on the piston rod 24 is prevented from being pushed out. The counter bore 102 of the housing 88 receives the seal ring 104 and the piston rod
Provides a fluid tight seal between 24 and housing 88. The wiper 101 prevents contamination of the bearing. The inserted annular plastic bush 103 guides the piston rod 24.

A piston rod assembly 34 is slidably received within cylinder body 32 for reciprocating movement between an extended position as shown in FIG. 3 and a retracted position as shown in FIG. Piston 106 is configured to receive an annular bearing 110 with a groove 108 formed therein. An annular bearing 110 connects the piston 106 to the cylinder body 32
Guide for reciprocation inside the. A second groove 112 formed in piston 106 preferably receives a low friction, low wear slip ring 113 supported by an O-ring 114 to flow between the outer surface of piston 106 and the inner surface of side wall 42. Provides a tight seal. A central passage 116 through piston 106 receives valve 118. The valve 118 allows a substantially free flow of compressed gas from the second gas chamber 68 to the first gas chamber 64, and a gas flow from the first gas chamber 64 to the second gas chamber 68. At least partially. Preferably, valve 118 is a check valve that substantially stops fluid flow from first gas chamber 64 to second gas chamber 68. The valve 118 has a valve head 120 that is flexibly biased against a valve seat 122 by a spring 124 or the like.

To connect the piston 106 to the piston rod 24, the split ring retainer 130 has a rib 132 extending substantially radially inward. The rib 132 is configured to be received in an annular groove 134 of the piston rod 24. The split ring retainer 130 is
Secured to the piston 106 by one or more cap screws 136 that extend into the threaded blind bore. The movement of the piston rod assembly 34 with the piston rod 24 extending out of the cylinder body 32 to its extended position is accomplished by the housing 88 of the bearing and seal assembly 86.
And the split ring retainer 130 is engaged.

Operation A specific, but not exclusive, use of this gas spring is the double draw ring that extends and pulls upside down and drawn as shown in FIGS. Upper die 12 and lower die
In order to form the sheet metal blank 20 received between the 16, the upper die 12 is advanced by the upper press platen 14 toward the lower die 16 to form the blank 20 therebetween. As shown in FIG. 5, the gas springs 13, 10 held by the upper die 12 and the lower die 16 have extraction rings 26, 27 there. The draw rings 26, 27 engage the blank 20 and position and hold the blank 20 as the dies 12, 16 mold it. After the draw rings 26, 27 engage the blank 20, the upper press platen 14 advances further, thereby causing the piston rod 24 of the gas spring 10 of the lower die 16 to "bottom" as shown in FIG. Or until it reaches its fully retracted position. As shown in FIG. 7, as the upper press platen 14 advances further, the piston rod 24 of the gas spring 13 of the upper press platen 14 is moved to its fully contracted position, and the upper press platen 14 engages with the blank 20. And mold it. As shown in FIG. 8, when the upper press platen 14 is retracted, the piston rod 24 of the gas spring 13 of the upper press platen 14 returns to its extended position, and finally its withdrawal ring 26 becomes the lower withdrawal ring 27.
Separated from lower press platen 18 gas spring 10
Can return to its extended position (FIG. 9). Desirably, the gas spring 10 held by the lower die 16 engages and lifts the blank 20 from the lower die 16 after the blank 20 has been formed,
Thereby the blank 20 can be removed from the press 11 and the next blank to be formed can be inserted into the press 11.

To further control the return stroke of the piston rod 24 to more gently lift the formed blank 20 from the lower die 16, the gas spring 10 is configured as follows. When the piston rod 24 moves to its contracted position and when the piston rod 24 moves to its extended position, the compressed gas in the second gas chamber 68
Flows freely through the first gas chamber 64 to the first gas chamber 64;
The gas flow from the gas chamber 64 is restricted by the orifice 62 and is configured to control the rate at which the piston rod 24 returns to its extended position.

To accomplish this, the valve 118 held by the piston 106 is preferably a check valve. This check valve opens immediately as the piston rod assembly 34 moves to its retracted position, allowing gas in the second gas chamber 68 to flow substantially freely into the first gas chamber. During the return journey,
Valve 118 closes to stop gas flow from the first gas chamber 64 to the second gas chamber 68 via the valve. Thus, as the piston rod assembly 34 returns to its extended position, the gas in the first gas chamber 64 is compressed, and the gas leaks out only through the orifice 62, thereby reducing the amount of gas exiting the first gas chamber 64. The flow rate is controlled to reduce the rate at which the piston rod assembly 34 returns to its extended position. Gas flowing at a controlled rate from the first gas chamber 64 through the calibration orifice 62 passes through the passage 7 through the fluid passage 52, the branch passage 84, and the mounting plate 72.
0, bore 66 through base 44, and second gas chamber 6
Flowing to 8, the pressure in the first gas chamber 64 is reduced. By returning the gas to the second gas chamber 68,
Ensure that the piston rod assembly 34 returns to its extended position.

In particular, near or below the lower side of its travel from the extended position to the retracted position of the piston rod assembly 34, if the gas in the second gas chamber 68 does not compress further, the first and second gas The pressure in chambers 64, 68 will be approximately equal and valve 118 will close. At this point, there is a large difference in force across the piston 106 due to the large difference in the surface area of the piston 106 on which the gas in the first gas chamber 64 acts as compared to the second gas chamber 68. Thus, at least initially after the piston 106 has reached its fully retracted position, there is considerable force attempting to return the piston rod assembly 34 to its extended position. As the piston rod assembly 34 moves toward its extended position, the volume of the second gas chamber 68 increases to reduce the internal pressure. In one embodiment,
Piston rod assembly from less than 10% of return stroke
The force attempting to return 34 to its extended position is dramatically reduced, after which the net force on piston rod assembly 34 is sufficient to ensure that assembly 34 returns to its fully extended position. Can only be large. Of course, the flow of gas through the calibration orifice 62 controls the pressure in both the first and second gas chambers 64, 68 and thus the force acting on the assembly 34.

The compression of the gas and the large flow adjustment through the orifice 62 of the gas spring 10 generates considerable heat. If you do not dissipate that heat enough,
The temperature of the various seals within 10 will exceed the maximum allowable temperature. This will cause the seal to deteriorate or degrade and no longer provide a sufficient seal, and will cause the gas spring to fail. Therefore, preferably, a number of features are incorporated into the design of the gas spring 10 to increase the heat dissipation from the gas spring 10 thereby reducing the maximum temperature of the gas spring in use and increasing the cycle speed of the gas spring. Make it possible.

Among the functions designed to dissipate heat, the helical fluid passage 52 is used to conduct heat away from the heated compressed gas and the gas in the cylinder body 32 and especially the fluid passage 52. To increase the surface area in contact with the outer shell 30 formed of a material having high thermal conductivity. In order to increase the heat dissipated from the shell 30, cooling fins 36 are provided adjacent to the upper end of the shell, and
Can be received in the pocket to expose its outer surface to the outside air, so that at least some heat can be transferred to the atmosphere surrounding the shell 30 by convection.
The mounting plate 72 is also formed of a material having high thermal conductivity, and removes heat from the cylinder body 32 and the shell 30 by conduction. In addition, the mounting plate 72 is directly bolted to the lower die 16 or the lower platen 18 of the press 11 to serve as a heat sink, greatly improving the conduction of heat removed from the gas spring 10. Further, the heat pipe 40 received in the bore 38 of the shell 30 causes the fluid in the heat pipe 40 to evaporate at one end due to the heat inside the shell 30 and to condense at the other end to form a liquid. It takes advantage of the heat dissipation that occurs during the phase transition of the fluid, such as returning. Each of these functions is designed to remove heat from the gas spring 10 to keep its maximum temperature within a range and increase the cycle speed of the gas spring 10.

Second Embodiment As shown in FIG. 10, in order to improve the cooling of the gas spring 10 ', a reservoir or a surge tank 150 is provided to cool the compressed gas inside. The compressed gas is interchangeable with the compressed gas of the gas spring 10 ', supplementing the cooling of the gas spring and increasing its cooling. The gas spring 10 'itself can be configured substantially the same as in the first embodiment, and therefore will not be described in further detail to the same extent as in the first embodiment.

In order to control the flow of compressed gas between the gas spring 10 'and the surge tank 150, a flow control valve 152 is provided instead of the gas filler valve 78 of the first embodiment. Accepted by. The flow control valve 152 preferably allows for a relatively free flow of gas from the gas spring 10 'to the surge tank 150 and allows for restricting the flow of gas from the surge tank 150 back to the gas spring 10'. I do. To achieve this,
As shown in FIG. 10, the valve 152 is a valve head 1 that is flexibly urged toward a valve seat 156 by a spring 157.
54 having a small orifice 1 through the valve head 154 even when the valve head 154 is engaged with the valve seat 156.
58 allows the fluid to flow. The gas flow from the gas spring 10 'to the surge tank 150 shifts the valve head 154 from the valve seat 156, and the gas flows
It can flow relatively freely through 152. The gas flow in the opposite direction from the surge tank 150 to the gas spring 10 'presses the valve head 154 against the valve seat 156, so that the fluid in this direction
It flows through only 158 and thus at a controlled rate.

The surge tank 150 preferably has a generally tubular side wall 160 welded to the lower end cap 162 to define an open ended cylinder. The groove 164 on the inner surface of the side wall 160 receives the retaining ring 166 during assembly. The lower end cap 162 communicates with the passage 70 of the mounting plate 72 of the gas spring via the valve 152 and the conduit 170 to form the through passage 16.
With eight. The upper end cap 172 is detachably held on the side wall 160 by a holding ring 166, and a seal ring 176 is provided.
Has an annular groove 174 having the inside. Seal ring 176
Provides a fluid tight seal between the upper end cap 172 and the sidewall 160. A gas chamber 178 is defined between the upper end cap 172, the side wall 160, and the lower end cap 162 and communicates with the passage 168 to provide a compressed gas exchangeable with the gas of the gas spring 10 'to reduce pressure buildup. It is configured to accommodate a supply to improve cooling of the gas spring 10 '.

Preferably, a copper or aluminum heat sink 180 is mounted on the upper end of the surge tank 150 and has a radial array 182 of fins that are exposed to the atmosphere to improve heat dissipation from the surge tank 150. . The heat sink 180 and upper end cap 172 preferably have central through bores 184, 186, respectively, into which the elongated heat pipe 188 is press fit. Heat pipe 188
Preferably has the same configuration as the heat pipe 40 of the gas spring 10 and can accommodate fluid at a controlled pressure. The fluid is designed to evaporate above a predetermined temperature, the evaporating fluid moves toward a heat sink in the heat pipe 188, and then condenses when the temperature of the evaporating fluid falls below a predetermined temperature. You. heat pipe
188 dissipates heat due to the phase transition of the fluid. Therefore, the heat released by the recondensation of the fluid
Dissipated to 180 to remove heat from surge tank 150. The recondensed fluid flows through heat pipe 1 in heat pipe 188.
Return via the shin structure element (not shown) inside 88 and start the process again.

The surge tank also has a substantially cylindrical heat collector 19.
Can contain zero. The heat collector 190 is formed of a highly thermally conductive material, such as aluminum or copper, and is preferably generally cellular or foamed to increase heat transfer from the gas to the heat collector 190. Having a plurality of cavities through which compressed gas can penetrate. Pressing, brazing,
Alternatively, the heat collector 190 is connected to the heat pipe 188 by the part to be soldered, and the increased temperature of the heat collector 190 is transferred to the heat pipe 188, and then the heat is transferred to the heat sink 180. A shoulder brazed or formed on the ring 191 provides a seal 1
Hold the heat pipe under 93.

Gas spring 1 such that piston rod assembly 34 of gas spring 10 'returns to its extended position.
During the return stroke of 0 ', the volume of the second gas chamber 68 increases and the gas in the first gas chamber 64 can return to the second gas chamber 68 through the orifice 62 and the fluid passage 52, Also, cooler gas from the surge tank 150 can return to the gas spring 10 'through the interconnecting conduit 170 and the passage 70 in the mounting plate 72. The cooler gas from the surge tank 150 supplements the cooling of the gas spring 10 ', lowering its temperature during use and allowing the cycle speed of the gas spring 10' to be increased.

Third Embodiment As shown in FIG. 11, a gas spring 200 according to a third embodiment of the present invention has a piston assembly 34 ′ with a modified piston 202. The piston 202
Calibration passage 20 therethrough between first gas chamber 64 and second gas chamber 68 to control gas flow therethrough.
With 4. Valve 118 preferably functions similarly to the first embodiment, allowing gas flow from second gas chamber 68 to first gas chamber 64, and from first gas chamber 64 to first gas chamber 64. The reverse flow to the second gas chamber 68 is stopped. In this embodiment, passage 52 and branch passage 84 are not required. In addition to these exceptions, gas springs
The 200 is preferably configured substantially similar to the gas spring 10 of the first embodiment, and thus the same parts are given the same reference numbers and will not be described in detail again.

As the piston rod assembly 34 'moves from its extended position to its retracted position, the valve 118 opens and the gas in the second gas chamber 68 is released from the first gas chamber.
Can flow relatively freely to 64. During the return journey,
As the piston rod assembly 34 'returns to its extended position, the valve 118 stops the flow of gas through the valve 118 from the first gas chamber 64 to the second gas chamber 68, such flow being limited to the through passage 204. Occurs. Through passage 2
The relatively small area flowing through 04 restricts or controls the flow of gas exiting the first gas chamber to control the rate at which piston rod assembly 34 'moves toward its extended position.

Fourth Embodiment As shown in FIG. 12, the gas spring 300 can have a modified piston rod assembly 302 received in a cylinder body 303. The piston rod assembly 302 is connected to the piston rod 306 by a split retaining ring 308 received in a groove 310 of the piston rod 306,
Annular piston 3 further held by small holding wheel 309
04. Piston rod assembly 302 is held in the cylinder body by engagement of piston 304 using a seal and bearing assembly (not shown) such as assembly 86 shown in the previous embodiment. The piston preferably holds a bearing 311 to guide the piston as it reciprocates within body 303, and an O to provide a seal between piston 304 and piston rod 306 and body 303. Holds ring 312, low friction slip ring 313, and O-ring 314.

Blind bore 316 of piston rod 306
Is a lateral passage 3 extending through the piston rod 306
18 and an opening to the first gas chamber 320.
Counter bore 322 includes a bore 316 and a second gas chamber 324.
Lead to.

Valve 326 received in counterbore 322
Has a valve head 328 flexibly biased against the valve seat 330 by a spring 332 and the like to control the flow of fluid through the valve 326. Passage 3 through valve head 328
34 allows the flow of fluid through valve 326 to be controlled even when valve head 328 is engaged with valve seat 330.

When the piston rod assembly 302 moves from the extended position to the retracted position, the second gas chamber 32
4 is reduced in volume and the valve head 328 is
From the second gas chamber so that the gas is
It flows relatively freely from 324 to first gas chamber 320 via valve 326. During the return stroke, as the piston rod assembly 302 retracts toward its extended position, the volume of the first gas chamber 320 decreases and the valve head 328 advances into engagement with the valve seat 330, and the gas is A passage 334 from the first gas chamber 320 to the second gas chamber
Flows only through passage 334 through valve head 328 at a limited rate controlled by the area through which the fluid flows.

By controlling the gas exiting the first gas chamber 320, the return speed of the piston rod assembly 302 is controlled in generally the same manner as described in detail for the gas spring 10. If some external cooling sources, such as circulating coolant, are not provided, or if another cooling or heat dissipation device is not provided, the heat generated in the use of this relatively simple gas spring 300 will cause its cycle rate to increase. May be quite limited. The piston rod assembly 302 is a gas spring 1
It can be made more compact than the assembly 34 of FIG. The piston rod assembly 302 can be fitted with a valve to be used in the gas spring, such as the valve 118 of the gas spring 10, and if necessary, configured like the gas spring 10 of the first embodiment. You.

Fifth Embodiment As shown in FIG. 13, a gas spring according to a fifth embodiment is described.
400 has a check valve 402 in a passage 404 formed in the piston rod 406 and leading to the first gas chamber 64. Piston 408 is formed from a ring. The piston 408 has an inner circumferential groove 410 for receiving a seal 412 abutting the piston rod 406, and an outer circumferential groove 414 for receiving a slip ring 415 and a seal 416 abutting the cylinder body 32. The piston 408 is held on the piston rod 406 by a retaining wheel 418 held by the piston rod 406 and a circumferential shoulder 420 of the piston rod 406. A split retainer 422 partially received in the piston rod groove 424 has a bearing 425 to guide the movement of the piston rod, and separates the piston rod 406 and the piston 408 from the bearing and seal assembly 68 within the cylinder body. Is held by the engagement of.

The remainder of the gas spring 400 is preferably constructed in the same manner as the gas spring 10 of the first embodiment, and the same parts are given the same reference numbers.
Therefore, the configuration and operation of the gas spring 400 will not be described in further detail.

Preferably, the gas spring 400 can be manufactured more easily than the gas spring 10 because the piston 408 has a relatively simple design. In addition, the passage 404, the shoulder 420, and the groove 424
06 can be easily formed.

Sixth Embodiment As shown in FIG. 14, a gas spring according to a sixth embodiment
500 has a configuration of a piston rod 502 and a check valve 504 that are preferably the same as the piston rod 406 and the check valve 402 of the gas spring 400 of the fifth embodiment.
Piston 506 has a guide 512 and outer slots 508, 510 that hold slip ring 513 and seal 514, respectively.
Having. Piston 506 surrounds piston rod 502 and is retained between piston rod shoulder 516 and retaining ring 518. The side wall 520 of the piston 506 is
And retains the piston rod 502 and the piston 506 in the cylinder body 32 as in the previous embodiment.

In this embodiment, as shown in FIG. 14, when the piston rod 502 is in its extended position, the orifice 62 is closed by a piston guide 512 or the like,
Or sealed to hold some compressed gas in the first gas chamber 64. The compressed gas in the first gas chamber 64 resists the initial opening of the check valve 504 as the piston rod 502 moves toward its retracted position, reducing the impact on the gas spring or the initial force. Let it. After a short period of time when the piston rod 502 moves toward its retracted position, the pressure in the second gas chamber 68 will increase and open the check valve 504. Once check valve 504 is opened, gas spring 500 will operate in the same manner as gas spring 10 of the first embodiment.

The cylinder body 32, shell 30, bearing and seal assembly 68, and mounting plate 72 are preferably
It is configured like the gas spring 10 of the first embodiment. Therefore, the configuration of the gas spring 500 will not be described in further detail.

In either embodiment, the gas springs 10, 10 ', 200, 300, 400, 500 have their first gas chamber 64 or 320 and their second gas chamber 68 or 324.
To control the rate at which the piston rod assembly 34, 34 'returns from its retracted position to its extended position. Among other things, there is no need for electronic or manual control, and no return is delayed with hydraulic oil or other fluids. Rather, gas spring 10,
10 ', 200, 300, 400, 500 can be self-contained and use only compressed gas for piston rod assembly 3
4, 34 'controls the speed at which it returns. Preferably, the gas springs 10, 10 ', 200, 300, 400, 500 are provided with a great number of heat transfer functions, and the gas springs 10, 10', 200 are provided to improve the efficiency of the gas springs. , 300,
Improve the heat dissipation from 400, 500, prevent the gas spring from overheating and increase its maximum cycle speed.

[0042]

According to the present invention, there is provided a gas spring which is a self-contained type and which can control the returning speed of the piston rod using only the compressed gas. In addition, by improving the heat dissipation from the gas spring, it is possible to prevent the gas spring from overheating and to increase the maximum cycle speed thereof.

[Brief description of the drawings]

FIG. 1 is a side view of a set of punching dies having a gas spring embodying the present invention.

FIG. 2 is a bottom view of the gas spring.

FIG. 3 is a cross-sectional view of the gas spring taken along the line 3-3 in FIG. 2 and shown in an extended position of the gas spring.

FIG. 4 is a cross-sectional view of the gas spring of FIG. 3 in a contracted position of the gas spring.

5 is a partial schematic view of the press and the gas spring pair of FIG. 2, showing one of five different positions throughout the part punching cycle.

FIG. 6 is a partial schematic view of the press and the gas spring pair of FIG. 2 showing one of five different positions throughout the part punching cycle.

FIG. 7 is a partial schematic view of the press and the gas spring pair of FIG. 2 showing one of five different positions throughout the part punching cycle.

FIG. 8 is a partial schematic view of the press and the gas spring pair of FIG. 2 showing one of five different positions throughout the part punching cycle.

FIG. 9 is a partial schematic view of the press and the gas spring pair of FIG. 2 showing one of five different positions throughout the part punching cycle.

FIG. 10 is a cross-sectional view of an alternative embodiment of a gas spring having a surge tank.

FIG. 11 is a cross-sectional view of a modified gas spring embodying the present invention.

FIG. 12 is a partial cross-sectional view of another modified gas spring embodying the present invention.

FIG. 13 is a partial cross-sectional view of another modified gas spring embodying the present invention.

FIG. 14 is a partial cross-sectional view of another modified gas spring embodying the present invention.

[Explanation of symbols]

 10, 10 ', 13, 200, 300, 400, 500 Gas spring 24, 306, 406, 502 Piston rod 30 Shell 32, 303 Cylinder body 34, 34', 302 Piston rod assembly 38, 39 Blind bore 40, 188 Heat Pipes 64,320 First gas chamber 68,324 Second gas chamber 106,304,408,506 Piston 118,326 Valve 120,154,328 Valve head 122,156,330 Valve seat 150 Surge tank 152 Flow control valve 170 conduit

Claims (18)

[Claims] A body having a bore, a piston and a piston rod slidably received within said bore for reciprocating between an extended position and a retracted position, and containing pressurized gas. A piston rod assembly defining a first gas chamber and a second gas chamber configured to communicate with the first gas chamber and the second gas chamber to limit at least a gas flow rate A first passage having a portion sized to: a second passage communicating the first gas chamber with the second gas chamber; and a second passage in the second passage. A valve for controlling the flow of gas therethrough, wherein when the piston rod assembly moves toward its retracted position, the volume of the second gas chamber is reduced and the valve causes the second gas chamber to move through the second gas chamber. To allow gas in the chamber to flow through the second passage to the first gas chamber, such that the volume of the first gas chamber is reduced as the piston rod assembly moves toward its extended position. And the valve reduces the second
At least substantially stop the flow of gas through the passage of
The flow rate of gas through the first passage from the first gas chamber to the second gas chamber is controlled by the portion that restricts flow to control the flow rate of gas exiting the first gas chamber. A gas spring, wherein the gas spring includes a valve that is controlled and, as a result, arranged and configured to control the speed at which the piston rod assembly moves toward its extended position. 2. The gas spring according to claim 1, wherein said second passage is formed through said piston and said valve is retained by said piston. 3. The valve stops flow of gas from the first gas chamber to the second gas chamber.
The gas spring according to claim 2. 4. The valve has a valve seat and a valve head, the valve head being engagable with the valve seat to control the flow of gas through the second passage, and wherein the valve is The bore formed through the head defines the first passage through which gas can flow at a limited flow rate even when the valve head is engaged with the valve seat. 2 gas spring. 5. The gas spring according to claim 1, further comprising a shell surrounding said body, wherein said first passage is defined at least in part between said shell and said body. 6. The shell of claim 1 wherein said shell is formed of a material having high thermal conductivity and said first passage is somewhat detoured to increase heat transfer from the gas in said first passage to said shell. Item 5. A gas spring according to item 5. 7. The gas spring according to claim 1, wherein both the first gas chamber and the second gas chamber are configured to accommodate a pressurized inert gas. 8. The first gas chamber and the second gas chamber are spaced from the body and communicate with the first passage via a conduit to increase heat transfer from the gas spring. The gas spring of claim 1, further comprising a reservoir configured to receive a supply of compressed fluid to be exchanged for at least some gas in one of the gas chambers. 9. The gas spring of claim 5, further comprising a base plate, wherein the body and shell are mounted with the first passage at least partially defined in the base plate. 10. The gas spring according to claim 5, wherein said body is formed of steel and said shell is formed of aluminum. 11. The first passage is at least partially defined by a helical groove formed in the body.
The gas spring according to claim 5. 12. The gas spring according to claim 1, wherein said second passage is formed in said piston rod. 13. The gas spring according to claim 1, wherein said first passage is formed through said piston. 14. The shell, wherein the shell has a plurality of blind bores,
6. The gas spring of claim 5 including a heat pipe received in each bore to increase the transfer of heat removed from the gas spring. 15. A compressed gas from said second gas chamber having a body defining a chamber adapted to receive a pressurized gas, said gas being adapted to facilitate cooling of a gas and a gas spring. The gas spring of claim 1, further comprising a surge tank in communication with said second gas chamber for receiving compressed gas from said second gas chamber. 16. A gas pump, comprising: a second gas chamber disposed between the second gas chamber and the surge tank; and a second gas chamber disposed between the second gas chamber and the surge tank. 15. The gas spring of claim 14, further comprising a control valve configured to allow restricted flow of gas in the opposite direction. 17. The gas spring according to claim 15, wherein a body of said surge tank is formed of a material having high thermal conductivity. 18. The gas spring according to claim 1, wherein said piston stops fluid flow through said first passage when said piston rod assembly is in its extended position.